A bulldozer can be used on a variety of working sites. The blade can be used for a variety of different operations including digging, carrying of soil or other material, banking, compacting and levelling. The design of the blade and how it is used determine the efficiency of the bulldozer in a working situation. It is therefore important to maximise working efficiency by designing a blade which is easier to use and can perform at least one function better than an existing blade.
The ability of a blade to dig into the ground depends on the shape of the front edge, force for pressing the blade into the ground as well as the angle of the blade when it contacts the earth. U.S. Pat. No. 6,938,701 discloses one type of bulldozer blade in which the front edge of the blade has a width which is larger than the width between the tracks of the bulldozer which carries it. This front edge is straight and perpendicular to the direction of movement of the vehicle in a forward direction. On either side of the central section the blade is angled rearwardly and then forwardly to provide three separate sections of cutting edges. The side and end sections are connected in a V-type configuration which is completely behind the front edge of the central section.
In operation the blade must be tilted downwardly with respect to its non-operative position in order to engage a ground surface.
The blade described in this patent suffers a number of drawbacks which reduce overall operating efficiency. One of the disadvantages with the blade design is that the blade must be tilted upwardly in order retain material effectively on its surface. Furthermore, the blade must be tilted downwardly to engage a ground surface. Furthermore, the ability of the blade to cut through a ground surface is inferior to blades which have a point. On top of this material which is contacted by the front edge moves up the front face of the blade but interferes with excavation of further material in front of the blade. Any material which moves to the side of the front edge of the blade generally escapes beyond each edge of the blade if the blade moves too far forward without being tilted upwardly.
Other disadvantages arise from the shape of the front face and difficulties associated with effectively cutting into a ground surface.
For existing bulldozers, present practices when loading material onto a blade that is tight is to use the corner tips to achieve penetration and roll the blade back once loaded. This has a tendency to turn the dozer towards the corner tip as the load is now off centre. If the operator is not very experienced he will use the steering clutches in an attempt to keep the dozer moving straight. It has also been noticed that existing blades do not fill to full capacity when in operation.